Gamma glutamyl transpeptidase, a membrane bound enzyme, has been implicated in mechanisms of amino acid transport across the blood-brain-barrier, glutathione catabolism, and mental retardation. Recently, in preliminary in vitro studies in our laboratories it has been shown that ethanol has an activating affect on the activity of the enzyme in whole rat brain. Thus, there is the additional implication that the enzyme may be involved in the resulting depressant effects of alcohol on the central nervous system. The present proposal is undertaken as a means to elucidate the effects of chronic and acute alcohol administration on the biochemical properties and developmental patterns of the isoenzymatic forms of gamma glutamyl transpeptidase in rat brain. Studies to be conducted include attempts to: (1) determine the effects of alcohol on the cellular localization of the two isoenzymatic forms of the enzyme; (2) determine the effects of alcohol on the subcellular and regional distribution of the enzymes; (3) determine the effects of alcohol on the patterns of gamma-glutamyl transpeptidase activity during development; (4) determine the effects of alcohol on the biochemical and physical characteristics of the enzyme. Rats are to be administered alcohol by the method of Goldstein, via an inhalation chamber and pretreatment with pyrazole. Rats treated with alcohol and controls are to be compared regarding the regional localization, localization within central cellular elements and subcellular localization of the High and Low Km forms of the enzyme, gamma-glutamyl transpeptidase. The enzymes from each group of animals will be separated and purified and the biochemical properties compared. The Km for the substrate gamma-glutamyl p nitroanilide, molecular weights, pH optima and the need for co-factors will be determined. Ontogenital studies will be conducted to determine whether both isoenzymes develop simultaneously or independently of each other.